DynamoDB Auto Scaling

• DynamoDB Auto Scaling uses the AWS Application Auto Scaling service to dynamically adjust provisioned throughput capacity on your behalf, in response to actual traffic patterns.
• Application Auto Scaling enables a DynamoDB table or a global secondary index to increase its provisioned read and write capacity to handle sudden increases in traffic, without throttling.
• When the workload decreases, Application Auto Scaling decreases the throughput so that you don’t pay for unused provisioned capacity.

DynamoDB Auto Scaling Process

1. Application Auto Scaling policy can be created on the DynamoDB table.
2. DynamoDB publishes consumed capacity metrics to CloudWatch.
3. If the table’s consumed capacity exceeds the target utilization (or falls below the target) for a specific length of time, CloudWatch triggers an alarm. You can view the alarm on the console and receive notifications using Simple Notification Service – SNS.
   1. The upper threshold alarm is triggered when consumed reads or writes breach the target utilization percent for two consecutive minutes.
   2. The lower threshold alarm is triggered after traffic falls below the target utilization minus 20 percent for 15 consecutive minutes.
4. CloudWatch alarm invokes Application Auto Scaling to evaluate the scaling policy.
5. Application Auto Scaling issues an UpdateTable request to adjust the table’s provisioned throughput.
6. DynamoDB processes the UpdateTable request, dynamically increasing (or decreasing) the table’s provisioned throughput capacity so that it approaches your target utilization.

AWS Certification Exam Practice Questions

• Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
• AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
• AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
• Open to further feedback, discussion and correction.

1. An application running on Amazon EC2 instances writes data synchronously to an Amazon DynamoDB table configured for 60 write capacity units. During normal operation, the application writes 50KB/s to the table but can scale up to 500 KB/s during peak hours. The application is currently getting throttling errors from the DynamoDB table during peak hours. What is the MOST cost-effective change to support the increased traffic with minimal changes to the application?
   1. Use Amazon SNS to manage the write operations to the DynamoDB table
   2. Change DynamoDB table configuration to 600 write capacity units
   3. Increase the number of Amazon EC2 instances to support the traffic
   4. Configure Amazon DynamoDB Auto Scaling to handle the extra demand

References

DynamoDB_Auto_Scaling